Alternatively, or perhaps even concurrently, you can have a Proton instance without having Steam installed. Dunno how it works on Lutris, but besides being able to install Proton manually, you should also be able to install a few different versions of it through Heroic too. Dunno other means for that but probably are.
About the tool, thanks. I’ll keep it in mind.
About Heroic, it allows installing several versions of a few forks of Wine, Proton and Proton-GE included, and it’s installed on a folder specific from Heroic, instead of installing on the whole system.